1. Field of the Invention
This invention relates generally to an electronic flash light-emission controlling apparatus and a camera with a built-in electronic flash. More particularly, this invention relates to technics that are applied to a camera that can perform a shooting with an appropriate exposure by utilizing the electronic flash.
2. Description of Related Art
U.S. Pat. No. 6,029,015 discloses a camera whose electronic flash is used even under conditions (external light brightness) in which an appropriate exposure can be obtained without the light of the electronic flash. U.S. Pat. No. 5,765,057 discloses a camera that prohibits an electronic flash from emitting a light when the brightness exceeds a predetermined brightness and the subject distance is longer than a predetermined distance.
In the case of a programmed shutter that adjusts an exposure by determining an aperture and a shutter speed from an opening shape of the shutter, an opening value of the shutter is determined according to an exposure value calculated from the brightness and the film speed and a range of the opening value within which the electronic flash can emit a light. In the camera disclosed in U.S. Pat. No. 5,765,057 that prohibits the electronic flash from emitting the light when the brightness exceeds the predetermined brightness and the subject distance is longer than the predetermined distance, however, the electronic flash may emit the light and may not emit the light even if an expected value of an exposure by the electronic flash is the same. Thus, the camera may waste energy. That problem occurs especially when the subject distance is long.
Even under conditions in which a shooting is possible by an AE control, for example, when the external light brightness is enough, the light of the electronic flash cancels a shade. But, if the electronic flash is used when the subject distance is short, the exposure by the electronic flash is excessive with respect to a control target value due to a restriction of an opening value of the shutter for a light-emission control of the electronic flash.